With the arising and application of 3G and 4G technologies, wireless communications impose an increasingly high requirement on the transmission rate, and microwave photonics technologies have gradually become an important technology in wireless communications due to the advantage of high speed.
A wireless communication system generally includes a signal transmitter and a signal receiving device. In the prior art, a signal receiving device based on microwave photonics technologies is provided. As shown in FIG. 1, the signal receiving device is disposed with a local oscillator, and the local oscillator is formed by an optical frequency comb generator (Optical Frequency Comb Generator, abbreviated as OFCG) and two optical phase locked loops (Optical Phase Locked Loops, abbreviated as OPLLs). The OFCG is configured to generate two optical signals which have their respective frequencies are V3 and V4 and have different frequencies, in which frequencies of the two optical signals are locked by the OPLLs, then enter a traveling wave uni-traveling-carrier photodiode (Traveling Wave Uni-Traveling-Carrier Photodiode, abbreviated as TW-UTC PD), and are mixed with a signal which has its frequency is V1-V2 and is received from an antenna after being outputted from the TW-UTC PD. A mixed signal enters a band-pass filter and is filtered, and then amplified, to obtain a medium frequency signal. The medium frequency signal can be directly input into a high-speed analog-to-digital converter (Analog-to-Digital Converter, abbreviated as ADC) or a down converter for baseband signal demodulation.
After the optical signals generated by the local oscillator pass through the TW-UTC PD, a noise is introduced, so an error is inevitably caused after the optical signals generated by the local oscillator are mixed with the signal received from the antenna, which in turn influences the accuracy of the whole system. When a microwave carrier frequency needs to be adjusted, the OFCG needs to be adjusted, and the process is troublesome, inflexible, and less accurate. The OPLL, the OFCG and the TW-UTC PD have a high market price, and a high cost.